A thin film transistor liquid crystal display (referred to as TFT-LCD) has advantages such as small volume, low power consumption, no radiation, and low manufacturing cost, and thus dominates in the current market for a flat panel display. As the image resolution (PPI, pixels per inch) of a product is increasing and a bezel is narrowing, at a periphery region of a display, a new technology is required to achieve connection between signal lines of different layers.